Lens-grinding machinery



Mar. 13, 1923. V 1,448,699

H. K. .PARsoNs mus GRINDING MACHINERY Filed June 27; 1921 2 sheets-sheetl INVENTOR HAROLD KPARSONS HvHsdW Wm ATTORNEYS Mar. 13, 1923. v

' H. K. PARSONS -LENS GRINDING MIXCI-IINERY Filed June 27. 1921 INVENTORHAROLD K. PARSONS ATTORNEYS ing Patented Mar. 13, 1923.

' UNITED STATES mom) K. rnnsons'or. sou'rnnmnen, MASSACHUSETTS.

LENS-GRINDING MACHINERY. 7

Application filed June 27, 1921 Serial N0. 480,726. i

To all whom/it may concern: I i

Be it known that I, HAROLD K. PARSON a citizen of the United States,residing at Southbridge, in the county of Worcester and State ofMassachusetts, have invented;

certain new and useful Improvements in Lens-Grinding Machinery, ofwhichthe following is a specification.

This invention relates to improvements in lens grinding machinery andhas particular reference to novel and improved machinery especiallyadapted for use in the formation of bifocal orother high grade lenses.One of the leading objects of the present invention is the provision ofa novel and improved balanced construction of device for use in theformation of target type onepiece bifocal lenses which will greatlyincrease the speed of grinding of said lenses. A further object of the.present invention is the provision of a machine which will accomplishmaximum grinding in minimum time and in which substantially equalgrindwill occur at all points onjthe glass so that there will be .nodelay of the grinding due to high Or low points, unequal a rasions,orthe like.

Other objects and advantages of my 1mproved construction should bereadily apparent by reference tothe followingspecification taken inconnection] with the accompanying drawings, and it will be under stoodthat I may make any modifications in the specific details illustratedwithin the scope of the appended claimswithout departing from orexceeding thejspirit of the invention. 1

Figure I represents machine embodying my improvements.

Figure II represents an enlarged fragmentary sectional v'ew as on theline II--II of Figure I.

Figure III represents a vertical sectional a side elevation of; a

, view through a single surface grinding machine. y I

Figure IV represents a semi-diagrammatic plan view of a lens bringingout the relationship thereto of the parts shown in Fi e III. igure Vrepresents a plan view of the completed blank.

' In the drawings, the numeral 1 designates the main horizontal shaft ofmy machine, having rotatably mounted thereon the driven sleeves 2 and 3which maybe held in spaced relation as by the central collar 4: andretained in position on the shaft as by the adjustable collars 5. Eachof these sleeves is provided with a drive ulley 6 for rotation of thesleeve, thetwo s; eeves being operated in opposite directions and eachbearing a grinding or abrading wheel or disc member 7 This member 7 maybe designed to produce either one ormore than one surface on the articletobe ground, as may be preferred.

Figures I and II illustrate a: construction in which a bifocal lenshaving a distance portion or surface 8 and a central near or readingportion 9is supported by the holder 10 in operative relation to myimproved grinding discs. These discs 11 and 12 are j shown in Figure IIas provided with the outer curvature proper to reproduce the surface 8and with an lnner curvature as at 13' suitable ,to reproduce the surface9. l

It willbeunderstood'that with the holder 10 rigidly carried on thespindle 1 1 carried by the bracket 15, if desired but a single one ofthe discs can be employed, the parts being so turned thatthedirection'of rotation of the glass surface 8 in contact with the wheel11 will be opposed to the direction of rotation of the disc. In this waymaximumabrasion and cross grinding will be produced, in the event thatthe wheel 12 is also employed for this grinding operation, whichstructure gives a better balanced wheel and one putting less strain onthe spindle 14. In the event that this structure is ems ployed, however,the wheels 11 and '12 are rotated through their respective drive pulleysGin opposite instead of the same direction. Each will be opposed to thedirection of rotation of'the; glass blank in immediate engagementtherewith.

,I am aware th t priorto my invention someattempts have. been made touse a wheel grinder 'of "the general appearance of my construction. IThis, however, has been open to one fatal difficulty in that whiletheoretically the lens was balanced on the surface of the wheel andequal grinding was taking place at all points asa practical and actualfact the lens over a portion of the wheel was travelling in the oppositedirection and over a portion in the same direction as the surface of thewheel. The result was that the abrading action could take place only sofast as the opposed parts at the side movingin the same direction woreaway, this side tending to hold up the glass at the opposite side, theabrading action there be ing slower and tending to produce anintermittent abrading action at the opposite side, since as the twoopposed parts come into engagement they will tend to momentarily Wearaway rapidly and then as'slightly held up at the other side to be aslight space in which the abrasive may collect to produce a scratchingrather than proper abrading' ac ion-f I my improvement thesedifficulties are all done away with since the entire grinding action-iswith opposed parts or parts movingin the opposite direction and the twohalves or sides both have'an equal abrading action tending to wear awayequally and to greatly increase the speed of operation.

In Figure II it is to be noted that I have shown a simultaneousgeneration of two surfaces upon the glass disc, but it will beunderstood that I may, as shown in Figure HI, generate but one, or theouter surface, withthis form of mechanism and form the 1 inner orsurface 9 by a separate mechanism.

In this event I preferably centrally provide the trough portions 16 atthe inner faces of the two Wheels, and the outer trough portions 17. IThe purpose of these is to collect and receive abrasive forced out bythe rotatinglens blank or disc 8 so that the same will not work downintothe bearings of the machine, but will be received in the trough andthrown off as the wheel rotates into a suitable enclosing pan 19,, thussatisfactorily protecting the, bearings from accidental abrading action.

Figure IV shows the general principle of operation of my improvedmechanism, in that the lens blank or disc itself is being rotated in aclockwise direction, the wheel 11 being rotated toward. the front andthe wheel 12 toward the rear, this action serving most satisfactorily toproduce the target shaped blank shown in Figure V. y

I claim: I .1, A--lens grinding machine inoluding'a 'Work holder, a pairof spaced abrading members opposed to the work holder for simultaneouslyengaging. the work carried thereby, means for relatively shifting saidab-rading members in opposite directions, and means for rotating thework holder about an axis at right angles to the axis on which saidparts are shifted.

2. A lens grinding machine including a main shaft, a pair of sleevesrotatably mounted on the shaft adjacent each other, means for rotatingthe sleeves in opposite directions, and an abrading disc carried byeach-sleeve, substantially as and for the purpose described.

3; A lens grinding machine including a main shaft, a pair of sleeves:rotatably mounted onthe shaft adjacent eachother, means for rotating thesleeves in opposite directions, an abrading disc carried by each sleeve,and a work holder spanning the discs to presentthe work simultaneouslyto both of said discs.

d. Alens grinding machine including a flanges carried by the edges ofthe disc providing abrasive receiving grooves.

6f A' lens grinding member in the form of a centrally splitcenterse'ction of a sphere, the two sections formed by the central splithaving a common outer spherical curve and aniniier curve forming acontinuous are in transverse cross section, and meanjs for 1 rotatingthe two halves in opposite directions'. 7.. Alexis grinding memberin"the form of a centrallylsplit' center section of a sphere, the twosections formed the central split having a common outer sphericalcurve-and an inner curve forming a continuous arc in transverse crosssection, means for rotating the two halves in opposite directions, andmeans for rotating an article to 'begroun'd in a directionopposedtothedirection of rotation of the discs and in simultaneousengagementwith both of said discs.

In testimony whereoflj have affixed my signature, in presence of twowitnesses.

HAROLD K. PARSONS.

lVi'tnesses: I i i SUSAN 'CAsAzzA,

Es'rH R M. LATFLER. i

